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Linux Isn't Alone With OpenGL Driver Issues

07-31-2012, 01:50 PM

Phoronix: Linux Isn't Alone With OpenGL Driver Issues

While the open-source Linux graphics drivers may not be up to scratch with the proprietary Linux graphics drivers from NVIDIA and AMD in terms of features, power efficiency, and performance, Linux isn't the only operating system with less than desirable OpenGL drivers. I've been surprised by the OpenGL issues under OS X 10.8 "Mountain Lion" with the Retina MacBook Pro...

Is it just me or is it really not easy to find out how the graphics drivers on mac os are developed?

Some people think apple takes the nvidia/amd/intel drivers and just build a wrapper for their kernel/gui/whatever.
But then, why does it only have OpenGL 3.2?
So some people think that apple does all the driver development themselves, of course with the help of nvidia/amd/intel. But really, why would you as a company want to develop three drivers at the same time?

Comment

Is it just me or is it really not easy to find out how the graphics drivers on mac os are developed?

Some people think apple takes the nvidia/amd/intel drivers and just build a wrapper for their kernel/gui/whatever.
But then, why does it only have OpenGL 3.2?
So some people think that apple does all the driver development themselves, of course with the help of nvidia/amd/intel. But really, why would you as a company want to develop three drivers at the same time?

Does anybody have insight how that all works?

My understanding is that both Apple and the GPU makers participate. I believe Apple writes the OpenGL front-end bringing in the OpenGL code and processing it (through LLVM?) into an intermediate form. GPU makers then write their drivers as plug-ins to take that intermediate form and interface it with their hardware. Because Apple controls the front-end, OpenGL support moves at the pace that Apple dictates in terms of new features/extensions, since even if GPU makers base their OpenGL driver on their Windows code with more features, the front-end wouldn't be able to understand it to pass it on to the GPU. Apple also writes a software renderer that they seem to like to keep pretty feature comparable with the GPUs. This might contribute to the slow pace of OpenGL support on Mac if Apple waits on getting their software renderer updated before enabling new OpenGL extensions. Now that even Intel IGPs have good hardware support and performance, the software renderer may not be that important anymore. I'm not sure if it's true or not, but I remember reading that AMD takes more responsibility for their Mac drivers whereas nVidia and Intel driver work often falls back on Apple themselves. Certainly AMD does seem to be more active on Apple's OpenGL mailing list.

In terms of finicky Mountain Lion support, I'm one of those that like to wait for point updates or service packs to be released before updating.

Comment

My understanding is that both Apple and the GPU makers participate. I believe Apple writes the OpenGL front-end bringing in the OpenGL code and processing it (through LLVM?) into an intermediate form. GPU makers then write their drivers as plug-ins to take that intermediate form and interface it with their hardware. Because Apple controls the front-end, OpenGL support moves at the pace that Apple dictates in terms of new features/extensions, since even if GPU makers base their OpenGL driver on their Windows code with more features, the front-end wouldn't be able to understand it to pass it on to the GPU. Apple also writes a software renderer that they seem to like to keep pretty feature comparable with the GPUs. This might contribute to the slow pace of OpenGL support on Mac if Apple waits on getting their software renderer updated before enabling new OpenGL extensions. Now that even Intel IGPs have good hardware support and performance, the software renderer may not be that important anymore. I'm not sure if it's true or not, but I remember reading that AMD takes more responsibility for their Mac drivers whereas nVidia and Intel driver work often falls back on Apple themselves. Certainly AMD does seem to be more active on Apple's OpenGL mailing list.

In terms of finicky Mountain Lion support, I'm one of those that like to wait for point updates or service packs to be released before updating.

Yep. My understanding is that it's somewhat similar to the way Microsoft handles Direct3D on windows - they write the high level API code, but still require the GPU makers to then handle the output from that and figure out how to run it on their hardware.

Comment

I have four Macs in the house and the three with Nvidia graphics are having difficulty running Windows 7 in Parallels with 3D enabled. The Mac with ATI isn't having the problem. I've been hearing alot of Hackintosh people having problems as well with Nvidia graphics since updating to Mountain Lion.